The primary objective of this research is to gain further insights into the mechanisms of protein secretion and its control, with attention focused on the Golgi complex and the participation of each of its components in the secretory process. The approach proposed to achieve this goal is a) to analyze the sites, pathways and control mechanisms for secretion of pituitary hormones, especially the glucoprotein hormones; b) to attempt to work out in detail the flow diagram of secretary products within the Golgi complex; and c) to determine the distribution of glycosyl transferases among components of the Golgi complex. The approach used to investigate these problems will combine the classical methods of experimental endocrinology with electron microscopy, autoradiography, enzyme cytochemistry and cell fractionation.